investigation of the possibility of increasing efficiency of pinoxaden and clodinafop by different application methods of these herbicides

background and objectives: nowadays herbicide reduction and different approaches leading to this goal like split application have been brought to attention. at split application, recommended or reduced doses divided in such a way which half of dose applied at one growth stage and the other half will use at next growth stage and finally all used doses are equal to recommended or any other reduced doses. in this approach in comparing with the simple application weed control duration will extend. although using reduced doses of herbicides to control weeds require long lasting information on seed bank of weeds so the crop yield loss by increased weed society will not occur. the goal of this experiment was to evaluate the possibility of reducing pinoxaden and clodinafop by different application and study the time interval application on herbicides efficiency at split application treatments on a. ludoviciana and p. minor as important weeds of wheat fields.materials and methods: greenhouse experiments were carried out to investigate the efficiency of single and split application of pinoxaden to control phalaris minor and clodinafop to control avena ludoviciana. the influence of time applications interval and the ratio of the two applications doses were studied. these herbicides were used as simple and split application. simple application treatments were applied at four stages g1 (2 leaf stage) g2 (3 days after first stage), g3 (7 days after first stage) and g4 (14 days after first stage) of a. ludoviciana and p. minor. at split application treatment 50 or 25% herbicide doses were used at g1 stage and the rest of them (50 or 25%) applied at g2, g3 and g4 stages. results: the study revealed that both single and split applications efficacy decreased as application timing was delayed but this reduction was more highlighted at single spray. 75:25 ratio approximately at all application timing showed more activity to control a. ludoviciana and p. minor. p. minor shows variable response to split application. although split application had appropriate control of p. minor but its difference with single application of clodinafop was not significant.conclusion: overall it could be concluded that single application treatments, had enough control at early stages of a. ludoviciana and p. minor but as these weeds were more grown, the efficiency of single application reduced and the efficiency of split application treatments depending on the type of weed species could be successful (a. ludoviciana) or had no significant differences with the single application treatment (p. minor).